WO 00/05307, WO 02/067906, and WO 2004/019918 describe cationic aminoalkyl acrylate copolymers and the use thereof as coatings and binders.
WO 2009/016258 discloses the preparation of the aqueous polymer dispersions of cationic polymers based on N,N-diethylaminoethyl methacrylate as are used according to the invention and the use thereof for coating drugs.
The term “solid dispersion” describes systems in which the active ingredient is embedded in the polymer matrix in the form of microdisperse domains. Such systems are true solid dispersions in the sense that the disperse phase and the continuous phase are solid phases.
Furthermore, the term “solid dispersion” also comprises so-called “solid solutions” in which the active ingredient is present in molecularly disperse form embedded in the solid polymer phase (the matrix). Such solid solutions lead, for example when used in solid pharmaceutical presentation forms of a sparingly soluble active ingredient, to an improved release of the active ingredient. An important requirement of such solid solutions is that they are stable, i.e. that the active ingredient does not crystallize out, even upon storage over a prolonged period. Furthermore, the capacity of the solid solution, in other words the ability to form stable solid solutions with the highest possible active ingredient contents, is also of importance.
The use of so-called “solid dispersions” for improving the solubility and bioavailability of drugs, and the preparation thereof by means of dissolving processes or melt extrusion is generally known, thus for example from “Ch. Leuner, J. Dressman, European Journal of Pharmaceutics and Biopharmaceutics 50 (2000) 47-60”. The use of cationic aminoacrylates such as Eudragit® E is also described in general terms in this literature reference.
However, it has been found that Eudragit® E, which is also marketed as Eudragit® E PO, still leaves something to be desired in terms of the stability of the solid dispersion and the loading capacity with active ingredient. Often, at higher active ingredient loadings, active ingredient crystals or relatively large active ingredient domains are produced.
However, the highest possible loading capacity is of great importance.